Distinguishing viruses responsible for influenza-like illness

Flu Shot Side Effects Like Fatigue Don't Mean You Have The Flu, But They Do Exist—Here Are The Ones To Know About

During a normal season, the flu affects five to 20 percent of the population. That's tens of millions of individuals in the United States alone. And the severity of the virus varies—some people will experience mild symptoms, while others die from the flu. According to the World Health Organization, the seasonal flu kills somewhere between 290,000 to 650,000 a year.

While this may sound scary, the good news is the spread of the influenza virus can be slowed. Thanks to the flu shot, protection is possible—and even if you do get the flu, the flu shot typically means symptoms are less severe. In other words, most experts say getting the flu shot is a good idea, especially with the COVID-19 pandemic still around. But it's worth noting that some individuals will experience side effects.

While most flu shot side effects are relatively harmless (if uncomfortable), here's what you should know about potential side effects of the flu shot. Remember, they're not long-lasting, so don't let them discourage you from getting the shot!

Side effects of the flu shot Fatigue

"As your body is busy building immunity to the virus that has been inserted into it, you may feel a little tired," Dr. Chun Tang, MD, a physician at Pall Mall Medical, explains. "This is completely normal." To combat feelings of exhaustion and fatigue, try to get an early night and let your body do its work. You can also take naps, as needed.

Redness or swelling

The most common side effect of the flu shot is a reaction at the injection site, which is typically on the upper arm. "People often experience some injection site reactions like redness and swelling," Dr. Philip Kadaj, MD, a Michigan-based internal medicine specialist, tells Parade.Com. And while this may be uncomfortable, it is completely normal. Redness and swelling is a common side effect that usually only lasts a few days and goes away on its own.

Pain at the injection site

Another common side effect is pain at the injection site. Why? Because the flu shot is given intramuscularly. According to the CDC, you have a 10 to 64 percent chance of experiencing some muscle soreness in your upper arm. To combat discomfort, take an over-the-counter pain reliever, like Tylenol, Advil, or Motrin.

Headache

Some individuals will experience headaches after receiving the flu shot. In fact, according to the CDC, pain and discomfort is a relatively common reaction. The good news is this reaction is temporary. Individuals usually feel relief within 48 hours or less, and said pain can be treated using over-the-counter products, like acetaminophen and ibuprofen.

Body aches

In addition to headaches and injection site pain, the flu shot can cause body aches. As mentioned, discomfort is a common side effect of the flu vaccine—and all vaccines. As with other aches and pains, body aches can be treated using over-the-counter products.

Related: How to Treat a Common Cold

Low-grade fever

Another common side effect of the flu shot is a low-grade fever or fever of 101°F or less. As with headaches and body aches, this reaction usually resolves itself rather quickly. Your fever should go away within a day or two.

Related: Myths and Facts About the Flu

Nausea

Some individuals will become nauseous after receiving the flu shot; however, as with headaches, body aches, and a low-grade fever, the CDC notes this is a normal reaction.

Related: What Foods to Eat When You Have the Flu

Flu-like symptoms

In addition to the aforementioned side effects, some individuals will experience flu-like symptoms, including but not limited to malaise, a cough, and/or a runny nose. "Some patients have some 'flu-like' symptoms for 24-48 hours afterward," Kadaj says. "It is basically a sign of the immune system responding to the vaccine and starting the process of developing antibodies." If these symptoms become troublesome or problematic, over-the-counter medication can be taken. Rest is also helpful.

Related: What Do I Have: A Cold Or the Flu? 

And finally, while unlikely, severe allergic reactions are possible. "Life-threatening allergic reactions to flu shots are very rare," the CDC explains. "[However,] signs of a serious allergic reaction can include breathing problems, hoarseness or wheezing, hives, paleness, weakness, a fast heartbeat, or dizziness."

If you experience any of these symptoms, you should contact your physician immediately and/or call 911.

Next up, here are the best ways to prevent the flu.

Sources

View the original article to see embedded media.

Too Late To Get A Flu Shot? When You Should Get Vaccinated

If you didn't already get your flu shot in October, which was a good time to get it, the best time ... [+] to get vaccinated is as soon as you can after October. (Photo by Noam Galai/Getty Images)

Getty Images

It may be too late to dress up like Barbie or Ken for Halloween. It may be too late to dress up like Barbie or Ken for Thanksgiving dinner, too. But as long as it's still either the fall or winter season, it is definitely not too late to get the flu shot. As long as you are somewhere in the October through March timeframe, you probably want to get vaccinated against influenza as soon as you can.

That's because the influenza season in the Northern Hemisphere can extend all the way from as early as October to as late as May the following calendar year. In fact, until you've gotten well into the New Year, chances are you and everyone around you haven't even seen the worst of the flu season yet. Flu activity is typically highest from December through February with peak influenza virus activity most commonly occurring in February. That's why it's good idea to always secure your protection well in advance of Valentine's Day.

Now, flu activity can follow very different patterns each season. In the four decades from the 1982-1983 flu season through the 2021-2022 flu season, the peak of the flu season has been in February a total of 17 times. December has been the next most common peak month at seven times. January and March tied for third place at six times apiece. And October, November and April have been the peak months only once each, according to data from the Centers for Disease Control and Prevention.

There's a saying among epidemiologists that if you've seen one flu season, you've seen just one flu season. Every year can be different from previous years. Unless you have a DeLorean that serves as a time machine or some other way of traveling to and from the future, it's impossible to predict exactly what this current flu season will look like. You cannot be sure when peak flu activity will occur, how bad things will be or whether this will be the season when there is a surge in cases in the later spring.

If you haven't yet been vaccinated, it's a good idea to get the flu vaccine as soon as possible. Keep in the mind that the flu vaccine isn't like a trench coat and doesn't start protecting you the moment you get it. Your immune system has to first see the weakened or inactivated flu particles from the vaccine, essentially say, "WTF is this? This doesn't belong in my body!" and then mount an immune response against them, which can take up to two weeks.

This two-week lag time to protection is a big reason why it's important to get the flu vaccine now without further delay. This will help protect you in time for the last two weeks of December, which may be filled with interactions with other people, objects and surfaces, especially if you celebrate Christmas, Kwanzaa, New Year's Eve, New Year's Day and the annual unofficial holiday of going to stores to return all the presents that you didn't want but somehow received.

Late September to mid-October is typically the best time to get vaccinated against the flu to make sure you are protected before flu activity really starts to increase, as demonstrated by computer modeling studies published by our PHICOR Team in the scientific journals Vaccine, the American Journal of Managed Care and Medical Care. It is is possible to get vaccinated a bit too early, such as in August, since the protection offered by the flu vaccine may start waning after six months, leaving you less protected the following May when the flu may still be around.

Keep in mind that while the flu vaccine can offer good protection against the flu, it won't offer you 100% protection. Instead, its protection can vary from 30% to 60% depending on how well the flu virus strains put in the vaccines in the leadup to flu season end up matching the strains that actually circulate that season. So just because you got the flu shot already doesn't mean that you should stop washing your hands frequently and thoroughly, begin hugging and kissing people who may be coughing, sneezing, feeling run down or hot (hot temperature-wise, that is) and abandon all other infection prevention measures. Otherwise, your New Year's Eve may turn out to be a Flu Year's Eve.

Of course, reducing your chances of getting infected is not the only benefit of the flu shot. Even if you do end up getting infected, being vaccinated can significantly reduce the severity of your symptoms and your chances of getting hospitalized and dying. Most commonly, the flu will result in four to seven days of fevers, chills, coughing, a sore throat, a runny or stuffy nose, muscle or body aches, headaches, fatigue, vomiting, diarrhea or other not very pleasant symptoms. They can be so unpleasant that you end up missing school or work.

Things can get even worse, though, especially if you have a weaker immune system. Each year from 2010 through 2022, somewhere between 9.4 million and 41 million people have gotten sick from the flu, between 100,000 and 710,000 people have been hospitalized and between 4,900 and 52,000 people have died. Catching the flu is not the same as catching the common cold. The flu could leave you a lot more sick with some potentially terrible consequences.

Finally, even if you think you've had the flu already this year, it is still a good idea to get the flu shot. Many different microbes can cause flu-like illnesses such as respiratory syncytial viruses (RSV) and adenoviruses. So, unless you actually got tested for the flu, you cannot be sure if you've actually had the flu, meaning that its' probably still worth a shot.

The Flu Shot Is Really The Only Way To Shorten The Duration Of The Infection

The colder months are synonymous with flu season. Even though there are several health threats around right now, it's still important to know the signs and symptoms of the flu so you can get to a doctor if necessary and make sure you don't give it to others. And if you do come down with the virus, one of the main questions you might have is how long does the flu last?

First, let's get the timeline straight: Flu season occurs in fall and winter and typically peaks in February and December, according to the Centers for Disease Control and Prevention. And this year's flu season is already rearing its head.

"This is shaping up to be a severe flu season," says Neha Vyas, MD, a family medicine physician at the Cleveland Clinic. "There are more positive flu cases this year and also much earlier in the season than what's been seen in more than a decade."

So far, there have been at least 880,000 flu illnesses, 6,900 hospitalizations, and 360 deaths from the flu this year alone, the CDC reports. While most people associate the flu with a bad cold and take it to mean they are down and out for a few days, it can actually be life-threatening.

"The flu, before the COVID pandemic, killed between 35,000 and 50,000 persons in the U.S. Each year, usually about 200 children and the rest older persons, often with pre-existing conditions," says Susan E. Hassig, DrPH, MPH, an associate professor within the epidemiology department at Tulane University's School of Public Health. Pregnant women are also at higher risk for severe flu.

So, when it comes to the flu, you don't want to mess around. Here's how to recognize whether you caught the virus, how long the symptoms last, and what you can do to prevent getting sick in the first place.

Meet the experts: Neha Vyas, MD, is a family medicine physician at the Cleveland Clinic.

Susan E. Hassig, DrPH, MPH, is an associate professor in the department of epidemiology at Tulane University.

What are the symptoms of the flu?

If you think you have the flu, the symptoms can vary somewhat, says Dr. Hassig. But generally they include sudden high fever, headache, muscle aches, fatigue, sore throat, and nasal congestion or a runny nose.

"In severe cases, pneumonia, shortness of breath, cardiac problems, and inflammation of the brain can also develop, and generally require hospitalization and may result in death," notes Dr. Hassig.

How do you actually get diagnosed with the flu?

If you really want to find out if you have the flu, you may have to get tested for an official diagnosis.

"There are a number of different tests, similar to the methods used for SARS-CoV2 (antigen detection, rapid PCR, etc.) that can be done in a clinic setting (doctor's office, urgent care, or the ER)," explains Dr. Hassig. "But many clinicians will make a determination of influenza on the basis of patient symptoms only (perhaps after doing a test for SARS-CoV2), especially when we are in flu season."

So, how long do flu symptoms typically last?

For most adults and teens, the flu lasts for five to seven days, says Natasha Bhuyan, MD, an infectious disease specialist and family physician in Phoenix, Arizona. In children, flu symptoms like cough and fatigue can last two weeks.

One thing that can help shorten the flu's duration if you do get it is the flu shot. It can't completely protect you from the flu, but it greatly reduces your chances of getting the virus, and makes the whole experience less miz if you do. It's especially important for pregnant women and seniors to get the flu shot since the symptoms can last longer and be more dangerous for them (more on that below).

How long are you contagious when you have the flu?

Most people with the flu are contagious even before they show symptoms—for about a day or so, in fact, says Dr. Bhuyan. Teenagers and adults are the most contagious around three to four days into their illness, but can continue to be contagious for about a week after symptoms appear. Infants and older adults (with weaker immune systems) can be contagious even beyond a week after they show symptoms. These periods when you're contagious without appearing sick are what make the flu so easy to spread (again, this is why getting a flu shot is so important!).

The number one thing you can do to prevent the spread of the flu is to stay home and isolate yourself from others when you're feeling sick (even in the beginning, when you're just a little under the weather but suspect you might be getting sick). Take that time to stay in and rest up as much as you can.

What can make the flu worse or more dangerous?

The flu might not seem like a big deal to you, but it certainly can be for others. Flu symptoms can be more dangerous in certain populations, such as people with weakened immune systems, pregnant women, children under the age of 5, people in long-term care facilities, seniors, or those with underlying lung issues, like asthma.

If you're pregnant, flu symptoms are more likely to be severe because of changes that occur in a woman's immune system, heart, and lungs during pregnancy. This makes pregnant women (and women up to two weeks postpartum) more prone to serious complications that can result in hospitalization, according to the CDC.

The flu may also be harmful for a developing baby, as having a fever while you're pregnant can be associated with neural tube defects and other serious complications, per March of Dimes. This is why it's especially important to get your flu shot if you're pregnant, as it will also protect your baby from the flu after birth, since you'll pass your antibodies onto them during pregnancy (very cool!).

People over 65 are also at higher risk of serious complications from the flu, since the strength of your immune system decreases as you get older, according to the CDC. In fact, the CDC estimates that between 70 to 85 percent of seasonal flu-related deaths have occurred in people 65 years and older, and between 50 and 70 percent of seasonal flu-related hospitalizations have occurred among older adults.

Again, staying home and resting is key when you have the flu. Trying to push through your symptoms will only make you more fatigued and it will take longer for you to recover. Hydration is also particularly important, and if you exercise too much during the flu, this could be dehydrating, says Dr. Bhuyan.

"Anything that adds additional strain to your body can potentially delay your recovery from the flu. This includes things like not getting enough sleep, not staying hydrated, pushing yourself to continue to work, or even strenuous exercise," she says. "That being said, people have different severities of the flu and if someone has a mild case, it's okay for them to do light exercise in their home, away from others, while ensuring they are taking good care of the rest of their health as they recover."

How can you get over the flu more quickly?

First of all, give your immune system all the support you can. "To ensure your immune system is functioning at its best, be sure to stay hydrated, get plenty of sleep, and eat mostly natural plant-based foods," says Dr. Bhuyan.

There are many over-the-counter products that can provide symptom relief while you have the flu, like fever-reducing medication. There is also a prescription anti-viral medication that can shorten the duration of the flu and might be appropriate for certain people—just ask your doc if it's right for you, says Dr. Bhuyan.

How can you protect yourself from the flu?

The best way to prevent the flu is by getting a flu shot, says Dr. Bhuyan. Anyone older than six months can get it. You should also wash your hands frequently with soap and water. If you cough or sneeze, use a tissue and immediately throw it away. Avoiding sharing foods, cups, or utensils with anyone as well.

"If you have flu-like symptoms, avoid going to work or school. The same things that prevent the spread of COVID can also reduce the risk of flu transmission, such as masks and social distancing," says Dr. Bhuyan.

When should you see a doctor if you think you have the flu?

In prior years, many people with mild flu symptoms were able to recover at home without much intervention, says Dr. Bhuyan. However, during the COVID-19 pandemic, it's important from a public health perspective to understand if you have the flu or COVID-19, as management options may be different. "During COVID-19, anyone with flu-like symptoms should reach out to their family physician virtually to discuss if they should get any diagnostic testing for the flu or COVID," says Dr. Bhuyan.

"Most family physicians have virtual care options and they can advise any diagnostic testing or management," she explains. "Your family physician can also provide you with guidance on how long to quarantine or isolate and when you can return to work or school."

You Might Also Like

---